Sorry to bang on but I want to get the record straight. The most definitive
recent research has been based on Antaractic ice-core samples and was
published in Nature in June 1999. () Climate and Atmospheric History of the
past 420,000 years from the Vostok Ice Core, Antarctica, by Petit J.R.,
Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M.,
Chappellaz J., Davis J. Delaygue G., Delmotte M. Kotlyakov V.M., Legrand M.,
Lipenkov V.M., Lorius C., Pépin L., Ritz C., Saltzman E., Stievenard M.,
Nature, 3 June 1999.) This altered the generally-held position in several
important ways. It showed, inter alia, that the present global warming
exceeds anything known of Earth for the entire past 420,000 years. It also
showed (Jose was right about this, but I think he drew the wrong conclusion)
that stabilisation mechanisms have existed hitherto which act to stop
runaway warming. Briefly, if the oceans warm up too much, changes in the
ocean circulation system precipitates a new Ice Age; thus glacial periods
are generally preceded by a rise in temperatures. Whether that mechanism
still works is a moot point; but if it does, then the most likely outcome of
this century's global warming will be to creat a new period of glaciation,
which would give Europe and Alaskan climate. I'm not sure how much comfort
we can derive from that (the Earth is currently in an era of Ice Agers
lasting several million years; the present Interglacial is the longest yet,
which is also a reason for supposing a new Ice Age may be imminent). What IS
certain is that man-made global warming has iuncreased instability and
therefore the likelihod of dramatic change.
Here are 2 useful urls:
http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/
where Petit et al's work is summarised and it is stated that:
>>Given all the new ice core data, what changes can we anticipate for our
climate? If CO2 has increased over the past 150 years as much as it
normally increases over thousands of years leading up to an interglacial
phase (about 80 ppmv), then we could expect as much as a corresponding
10-12C increase in temperature. But if half the historical temperature
increases have been due to orbital forcing and other factors, then we should
expect an increase of "only" about 5-6C, or 9-11F. <<
And
http://www.cnrs.fr/cw/en/pres/compress/mist030699.html
also dealing with the same topic.
The crucial point is that instead of doing what we can to reduce climate
instability by cutting down fossil fuel use and by startegies for carbon
sequestration, we are doing the exact opposite: burning off all that we
possibly can, while destroying the great carbon sinks which remain,
principally the rain forests. This kind of behaviour is known among
individual humans and it is called suicide.
Mark Jones
http://www.egroups.com/group/CrashList